Over fifteen million winged infusion, fistula, and pheresis needles are used each month in the United States to deliver sterile fluids to peripheral veins, or to access venous blood supplies for various extracorporeal treatments such as hemodialysis or plasmapheresis. Conventional winged needle assemblies include an elongated hub including flexible wing-like appendages (wings) and a needle attached to a first end of the hub. Conventional needles include "butterfly" needles having gauge in the range 18 G-30 G for administering medicines or IV fluids, and fistula needles having gauge in the range 12 G-17 G for moving blood between a patient and an extracorporeal circuit. Tubing is attached to the opposite end of the hub. The tubing may be attached to the inside of the hub (for high flow rate applications), or the tubing may be attached to the outside of the hub (since this type of connection typically is less expensive to achieve).
AIDS is now focusing the medical industry on ways to protect medical workers from infection induced by accidental needle sticks. A National Institute of Health survey in 1987 estimated that more than 800,000 accidental needle sticks occur each year in the United States, almost one accidental stick per nurse per year. Winged needles are just as likely to cause needle stick accidents as are hypodermic and other needles.
"Anti-stick" devices have been proposed, which have sought to sheath or guard a winged needle point after an injection. For example, U.S. Pat. No. 4,676,783, issued Jun. 30, 1987 to Jagger, et al., discloses a retractable winged needle assembly. The needle is mounted on a specially shaped winged inner tube (not a conventional winged needle hub), and the inner tube/needle assembly is slidably mounted within a specially shaped winged outer tube. The inner tube has a first pair of wings, and the outer tube has a second pair of wings. Neither the inner tube nor the outer tube is slotted. The outer tube's wings are gripped to push the needle into the patient's skin, and the inner tube's wings are gripped to retract the needle into the outer tube following an injection.
The apparatus of U.S. Pat. No. 4,676,783 has the disadvantage that both the inner and outer tubes are specially designed. Thus, the apparatus is not usable with a conventional winged needle assembly of the type including a needle mounted on a conventional winged hub. Nor may the winged needle assembly itself be used in a conventional manner. For example, the first pair of wings may not be used to stabilize (by taping) the needle while the needle tip is within a patient.
It has not been known until the present invention how to prevent accidental medical worker sticks due to winged needle injections, while also permitting use of conventional winged needles in a conventional manner.